1. Field of the Invention
The invention relates to an actuator for displacing the toggle or handle of a circuit interrupter, and more particularly relates to a handle actuator that includes a pair of spaced opposed abutment surfaces for bearing against the handle along an arcuate path coincident with the motion of the handle, to thereby move the handle between progressive positions in a positive motion that does not wear the handle.
2. Prior Art
Circuit interrupters characteristically have OPEN and CLOSED positions at which an electrical circuit coupling a power-supplying source or line to a power-consuming load is broken or made, respectively. In some circuits, circuit interrupters are used simply as manual switches, while in other circuits they are used in conjunction with switching controls and/or circuit protection devices operable to open or close the circuit automatically.
Circuit interrupters characteristically include some form of handle or toggle. Despite having handles, certain large circuit interrupters are generally unsuitable for manual operation because substantial force is needed to operate them. For example, 150 to 300 pounds may be needed to move the handle of a high power interrupter between the OPEN and CLOSED positions, to overcome the force of springs and the like arranged to force the contacts together when closed and/or to drive them apart when opened. Such circuit interrupters may require that the electrician (or perhaps an electrically powered operator) have the aid of some mechanical advantage to move the handle, such as a lever arm extension.
In some applications for circuit interrupters, a handle actuator is provided. The handle actuator typically has a pair of opposed and rigidly spaced abutment surfaces disposed on opposite sides of the handle in the directions of movement, bearing against the handle to drive the handle from one position to the other. The abutment surfaces are moved, with the handle between them, one of the abutment surfaces bearing against the rear side of the handle in the direction of movement, forcing the handle from one position to the other. The handle actuator can be coupled to a drive input that is operable either remotely, manually, or both ways, although not generally at the same time.
The drive unit can be coupled mechanically to a drive means, or an electrically driven arrangement can be provided. A remotely-operated drive input is often plugged into a network of several interrupters that are centrally controlled elsewhere, for example by a computer or the like. A manually-operated drive input is advantageous for allowing an electrician (or other operator) to override the central controller, on site. It may also be appropriate to use a mechanical or electromechanical drive unit to gang together a plurality of circuit interrupters, for coordinated switching of loads. Examples of handle actuators include the transfer switches disclosed in U.S. Pat. No. 3,778,633--DeVisser et al.; U.S. Pat. No. 4,398,097--Schell et al.; U.S. Pat. No. 4,760,278--Thomson and U.S. Pat. No. 5,081,367--Smith et al. All of those patents involve either a pair of molded-case switches or a pair of molded-case circuit breakers.
These known handle actuators have several deficiencies, in part because the means engaging the handle does not complement the movement of the handle accurately. The handle actuators have handle-engaging abutment surfaces which slide or roll relative to the handle bearing against the handle for driving between the open and closed positions. This sliding and/or rolling erodes the handle, and with continued operation causes the handle to break.
Whereas the means engaging the handle does not complement the handle movement, the spaced abutment surfaces must define a space larger than the dimensions of the handle. That is, the handle-engaging abutment surfaces are spaced such that the handle fits loosely between them. The loose fit is necessary to avoid the abutment surfaces binding the handle as the handle moves between its positions. However, the loose fit results in lost motion, and when the beating direction of the abutment surfaces is flipped-flopped, the loose fit causes one of the abutment surfaces to strike the handle, or vice versa. Impacts between the actuator and the handle aggravate the wear and erosion of the handle.
Known handle actuators may have bulky and involved mechanisms, which are relatively expensive and inconvenient to mount for operatively engaging the handle actuator and the circuit interrupter. Mounting is a particular problem for the popular molded-case type of circuit breaker.
Known handle actuator mechanisms may be too flimsy for heavy duty circuit interrupters. Known manually-operated handle actuators also are prone to twisting between the handle and the abutment surfaces because the abutment surfaces are coupled to the drive input asymmetrically. Twisting further shortens the life of the handle, which already has a limited life due to erosion and the like from wear against the actuator abutment surfaces.
What is needed is an improvement over the known handle actuators for overcoming these and other deficiencies, in a durable and inexpensive actuator arranged to minimize wear on the circuit interrupter handle or toggle.